Conversion of hydrocarbons



'Juli 2.5, 1944. A, ,1 ABRAMS ETAL 2,354,115'25 CONVERSION OFHYDROCARBONS Filed Oct. 22, 1941 INVENToRs Armand J' ram/' Patented,July 25, 1944y UNITED. STAT-Es PATENT OFFICE CONVERSION OF HYDROCARBONSArmand J. Abrams and Irving H. Welinsky, Dallas, Tex., assignors toSocony-Vacuum Oil Company, Incorporated, New York, N. Y., a corporationof New York Application-october z2, 1941, serial No. 416,018

4 Claims. (Cl. 196-50) p This invention is directed to a method for theconversion of liquid hydrocarbons having a boiling range in or near thegasoline boiling range for the purpose of increasing the anti-knockcapabilities of.such hydrocarbons. Such a process is usually carried outupon straight run gasolines, natural gasolines, fractions of eithernatural gasolines or of straight run gasolines, naphthas of eitherorigin which are near to or within the gasoline boiling range, or uponrelatively pure hydrocarbon compounds capable of being readily sotransformed into gasoline boiling yrange materials of higher anti-knockvalue.

Any process of this type is known generically by the expressionreforming of naphtha, which expression, as used, has a breadthsuilicient to embrace processes conducted both thermally andcatalytically, and in liquid phase, vapor phase, or mixed phase. Thepresent invention is directed to catalytic reforming of naphtha and incertain respects may be considered a specific invention under thegeneric-invention covered in the copending application Serial No.373,075, led January 4, 1941.

Catalysts are known for the reforming of naphtha. Thus, for example,silica-alumina and chromic oxide-alumina catalysts hav been -proposed.Thlsinvention is not concerned with a novel catalyst for the process butratheris directed to a method of controlling; the temperature in any ofthese catalytic processes using any solid reforming catalyst. For thesake of sim- -trol means, and heat has been supplied solely' through theexternal walls of the converters. We have found, however, thatsubstantially improved results are obtained even lwith chromicoxide-alumina catalysts where complete and adequate temperature controlis provided.

Therefore, it is an object of this invention to provide a -process ofreforming hydrocarbons which affords an improved temperaturecontrolexample, molten metal or molten salt, simulplicity, the inventionwill be discussed with par- 'ticular reference to chromic oxide-aluminacatalysts. However, it.will be.apparent.other re,.- forming catalystsmay be employed, and it is to be understood that the ,use of any solidreforming catalyst is considered within the scopeof the invention.

Heretofore, for the most part, the catalysts have been used in the -formof deep beds which may be stationary or moving, and the naphtha vaporsare passed through the bed. The requirements for and the dilllcultproblem of properly regulating or controlling the temperature throughoutsuch beds of catalysts, particularly taneously over a bed of a granularreforming catalyst under such conditions of rate and temperature that'the necessary heat of reaction will be supplied by the heat transfermedium. vThe rate of flow and the temperature of the heattransfer.medium can be'so regulated that a uniform temperature will resultthroughout the catalyst bed. At any one time, the bed of catalyst willhave the appearance of a tower of catalyst Vcontaining a ramication ofmetal mesh' in the form of streams of metal ('and/or salt). One distintadvantage associated with this-.method Lof supplying. heat to yacatalytic reaetionis that lt solves the heat transfer problem attendingsuch during regeneration of the catalyst, is well known to everyoneversed in the art.- Proper temperature control has been attained,however, by the use of internal indirect heat exchange equipment,

butsuch equipment increases the complexity of the apparatus required.Also, chromic oxidelalumina catalysts, which are notso sensitive to heatas.- say, alumina-silica catalysts, have been 'used without anyparticular temperature conreactions and allows the use of relativelylarge and simple converters. lIn other words, our process is animprovement upon prior practices in l that it solves the heat transferproblem associated with catalytic reactions and at the same time retainsthe desirable features of simplicity in design and cost of operation.

'I'he process may be readily understood by ref-v erence to the drawingattached hereto, the single `ligure of `which shows, in diagrammaticform, a

setup of apparatus suitable for accomplishing the process hereindescribed. In this -drawing there isa tower, chamber, -or housing l, inwhich, supported 'by a grid or'screen 2, there is a bed of catalyst I.Reactant vapors at or near reaction temperature are introduced throughpipe 4 and products of reaction are 5. A heated, liquid heat transfermedium is introwithdrawn through pille' mosphere of hydrogen,

.analyzed 2.5 weight .per cent tributor 1, and then through catalyst 3where it is in direct contact with and giving up heat to both thecatalyst mass 3 and the reactant vapors ilowing therethrough. The liquidheat transfer medium leaving the catalyst mass 3, is collected in pool 8at the bottom of the reaction vessel I and removed therefrom by pipe 3.This heat transfer medium is then forced through an external circuit bypump I wherein it flows through pipe II to heat adjuster I2, in whichits heat content is restored. Then, if necessary or desirable/ themedium ows through some carbon vcleaning operation as indicated at I3,after which it is returned to the reaction vessel I by pipe 3 15Obviously, if the catalystv to complete a cycle. l mass requires aregeneration necessitating' removal of heat, the same heat control meansus- I f ing a suitable heat transfer medium may be employed for suchheat removal, the equipment item I2 in this ease acting as a cooler.

A more full and complete description of opera- Itions under this generalplan of heat control by 1- physical or direct contact ,with a liquidheat transfer medium, together with many improved forms andmodifications thereof, is'given in the above-mentioned applicationSerial No. 373,075, filed January 4, 1941. Therefore, it is to beunderstood that any of the systems shown in that applicationmay be usedfor conducting the present process.

Liquid heat transfer media which may be used are molten metals andalloys, fused inorganic salts or mixtures of fused inorganic salts, or,indeed, any material liquid at the temperature of reaction, Vof lowvapor pressure at that temperature, stable at that temperature, and notentering into the reaction being accomplished other than to a catalyticextent. Of these media, the molten metals and alloys `are most desirableand preferable. Molten lead is typical of such a heat transfer material,but the invention must be understood as not being limited thereto.

, An important discovery of this invention is the fact that the catalystcan be regenerated repeatedly to optimum activity even though it iscarrying some lead. Thus, it seemsthat during the regeneration, the'lead on the catalyst is converted to lead oxides; however, as soon asthe catalyst is put back on streamthe'lead oxide is quickly reduced tometallic lead, and the process goes on with the catalyst at fullefilcieney.I In order to give a fuller disclosure of the invention,there are set forth below several examples of actual operation, but itis to be understood these specific examples are merely for purposes ofillustration.

. Example I- Y A catalyst was Vprepared by impregnating Vn inchactivated .alumina vchromic acid. After dryingat 250 C. in an atthepills contained approximately 15 mol per cent of CrnOs.

`'IhisJcatalyst was placed inl a reactor and a heptane cut (B. P.96-98.8 C.)l from a Mid- 05 Continent natural gasoline containing nooleflns or aromatics was passed through it at a temperature of 550" C.and a rate of- 0.3 liter of liquid feed per liter of catalyst per hour.The liquid product olens and 17.2 weight per cent of aromatics.

A duplicate experiment carried out with lead passing over the catalystunder non-ooding conditions yielded a liquid product which analyzed 7.3weight per cent oleiins and 34.8 weight per 75 pills with av solution of60 duced at pipe '3, flows into and through discent aromatics.Distillation data proved that the aromatics were mainly toluene. Thisvery significant increase in yield must be attributed to the uniformtemperature conditions which prevail in the catalyst bed while lead ispassing through it.

Example II An essentially depentanlzeg Mid-Continent natvural gasolinecontaining no oleilns or aromatics was passed over a` catalyst, preparedas in Exproduct contained 84.7 volume per cent hydrogen.

A duplicate experiment carried out with'lead passing over the catalystunder non-flooding conditions yielded a liquid product (84.8 weight percent of feed) which analyzed 20.9 weight per g cent oleflns and 34.9Weight per cent aromatics.

\ The gaseous product contained 87.0 voliune per cent hydrogen.

Here again, the higher yields of oleiins, aromatics and hydrogenillustrate how the process with lead passing over the catalyst is moreefcient. Furthermore, after each run, the catalyst was regenerated withoxygen-containing gases,

and the continuation of reaction in each case demonstrated that thecatalyst was brought back to initial activity, thereby establishing thatregeneration lof the catalyst in the presence of lead is not harmful.

Example III An essentially depentanized Mid-Continental natural gasolinewhith showed an A. S. T. M. octane number of 54.7 was reformed in amanner similar to that described in Example II. The

o product showed an A. S. T. M. octane number lof 71.8. y

,It will, of course, be realizedf that when regeneration of the catalystis appropriate to provide a unitary process that such regeneration iscontemplated as a part of the process herein dis- 'liodboiling range toprovide aromatic hydrocarbons i of gasoline boiling range whichcomprises passing the hydrocarbon charge stock in vapor form y through abed of catalyst under reforming conditions in direct contact with moltenlead as a 5s heat transfer'medium 'which is flowed through thecatalystbed in insufficient amount to flood the voids therein, removingliquid heat transfer medium from the catalyst bed, eliminatingcarbonaceous matter from said removed liquid medium and adjusting itsheat content for re-use in the catalyst bed, and returning the thustreated' liquid heat transfer medium to the catalyst bed. f

2. The process 'of catalytically' reforming hydrocarbonsl of boilingrange similar to gasoline to lproduce hydrocarbons of gasoline boilingrange and enhanced antiknock capability which comprises" passing thehydrocarbons in vapor form under reforming conditions through a bed of aregenerable, inorganic catalytic material,

maintaining thev catalyst bed and the hydrocarbons at the desiredreaction temperature by directly contacting said catalyst bed and'lsaidhydrocarbons with molten\lead as a heat transfer medium. and supplyingthe\necessary heat to said heat transfer medium when the heat transfermedium is out of contact with the catalyst bed.' A

3. The process of catalytically reforming hydrocarbons of boiling rangesimilar to gasoline to produce hydrocarbons of gasoline boiling rangeand enhanced antiknock capability which comprises passing thehydrocarbons in vapor l form under reforming conditions through a bedvof a regenerable, inorganic catalytic material,

maintaining the catalyst bed and the hydrocarbons at the desiredreaction temperature solely by flowing la, heated, normally solid melt,which is substantially inert under the reaction conditions, as a heattransfer medium -downto produce hydrocarbons of gasoline boiling rangeand enhance antiknock capability which comprises passing thehydrocarbons in vapor form under reforming conditions through a bed ofre generable, catalytic material, supplying all of the necessary heat tomaintain the hydrocarbons and catalyst bed at a desired reactiontemperatiire by flowing hot molten metal downwardly through'saidcatalyst bed in direct contact with said hydrocarbons at a rateinsuiiicient to flood the-voids therein, removing the molten metal fromthe bottom of said catalyst bed, supplying the necessaryvheat to saidmolten metaland recirculating it through said catalyst bed, andregulating the rate of admission of hydrocarbons to the catalyst bed sothat the over-al1 heat losses are at a rate substantially equal to theheat input supplied by the molten metal whereby a substantially constanttemperature gradient 20 is maintained in the catalyst bed.

4. The process of catalytically -x-eforming hydrocarbons of boilingrange similar to gasoline ARMAND J. ABRAMS. IRVING H. WELINSKY.

